Finding The Cause Of Noise - Humminbird 532769-3_A Installation Manual

Finding the Cause of Noise

Electrical noise usually affects the display with streaks or repetitive patterns on the
view. One or more of the following sources can cause noise or interference:
Possible Source of Noise
Other electronic devices
Other sonar devices
The boat's engine
Troubleshooting
Isolation
Turn off any nearby electronic devices to see if
the problem goes away, then turn them on one
at a time to see if the noise re-appears.
Turn off any nearby sonar devices to see if the
problem goes away, then turn them on one at a
time to see if the noise re-appears.
To determine whether the boat's engine is the
source of the noise, increase the RPMs while
the boat is in neutral and stationary to see if the
noise increases proportionately; if noise appears
when you rev the engine, the problem could
be the spark plugs, alternator, or tachometer
wiring. Replace the spark plugs with resistor
plugs, install an alternator filter, or route the
control head power and transducer cables away
from the engine wiring.
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